1. Technical Field
This invention relates generally to dye-ablative recording apparatus, and more particularly to an apparatus and process for collecting ablated materials and gasses to inhibit their deposit on critical parts of the system and to removing contaminants from the air.
2. Background Art
As used herein, the term "ablation" is intended to include removal of material by melting, vaporization, evaporation, sublimation, etc. In dye-ablation printing processes, a donor sheet including a material which strongly absorbs at, say, laser wavelength is irradiated. The absorbing material converts radiant energy to thermal energy, and transfers the heat to a dye in the immediate vicinity; thereby heating the dye to its vaporization (ablation) temperature. Further details of this process are found in GB 2,083,726A, the disclosure of which is hereby incorporated by reference.
In one ablative mode of laser imaging, a dye-ablative recording element includes an image dye, a light absorbing material, and a binder coated onto a substrate. The energy provided by the laser drives off the image dye at the spot where the laser beam hits the element, and leaves the binder behind. In ablative imaging, the laser radiation causes rapid local changes in the imaging layer, thereby causing the material to be ejected from the layer.
In some laser dye-ablation printing systems, the ablated material is physically transferred to a receiver medium. In such systems, the ablated material does not present a contamination problem. However, in other laser dye-ablation printing systems, the ablated dye explodes off the support into the surrounding air. Some of the ablated material in the surrounding air collects on the laser optics and deposits on the already-written portions of the recording element. The material build-up on the laser optics soon blocks much of the light, causing the printed minimum density D.sub.min to unacceptably increase. Deposit of the ablated material on the already-written portions of the recording element degrades the image by increasing the level of the D.sub.min of the image.
Commonly assigned U.S. Pat. No. 4,973,572 discloses a laser-induced thermal dye transfer element in which a positive image is obtained in the dye transfer element by imaging from the dye side of the element and blowing sublimed dye from the surface using a stream of compressed air. In large quantities, the "dust" of removed dye would be a problem.